Are hills meant for Nagas and plains for Assamese? How and when did the idea of hills and plains as isolated and separated terrain get solidified? Drawing references from the tour diaries and reports of the colonial officials, this article attempts to deconstruct the binary of ‘hills’ and ‘plains’ by emphasising on networks of communication and citing instances of trade and commerce between the dwellers of hills and plains. It draws a trajectory of the policies of the colonial and post-colonial governments, which began drawing lines between people and regulated their mobility. The sedentarisation attempted by the state, finally culminated as the border. The article is therefore an attempt in understanding the politics of border which hints towards two directions: impossibility of writing history and the continuous ‘unmaking’ of the nation.